Filtering object by keys in lodash

Question

I wrote the function below to return all keys in an object that match a specific pattern. It seems really round-about because there\'s no filter function in lodash for objects,

Answer 1

Here's a succinct way to do this with lodash - reduce() and set() are your friends.

_.reduce(data, (result, value, key) => key.match(pattern) ? 
  _.set(result, key, value) : result, {});

Answer 2

You can use pickBy from lodash to do this. (https://lodash.com/docs#pickBy)

This example returns an object with keys that start with 'a'

var object = { 'a': 1, 'b': '2', 'c': 3, 'aa': 5};

o2 = _.pickBy(object, function(v, k) {
    return k[0] === 'a';
});

o2 === {"a":1,"aa":5}

Answer 3

I don't think you need lodash for this, I would just use Object.keys, filter for matches then reduce back down to an object like this (untested, but should work):

export function keysThatMatch (pattern) {
  return (data) => {
    return Object.keys(data).filter((key) => {
      return key.match(pattern);
    }).reduce((obj, curKey) => {
      obj[curKey] = data[curKey];
      return obj;
    });
  }
}